Harold & Susan Vordos wrote:

Gold should never be melted in any kind of metallic vessel. Molten
metals are strong solvents of other metals, so the gold will be
contaminated, often rendering it useless as it loses its ductility,
depending on the alloying element.

so, if I wanted to melt a few old rings down into a cube or ingot, what
vessel or mold material can one use?